[Gvsig_english] QUESTION gvSIG -- Image files with fast rewrites

[Simon Cropper]

Hi Juan Lucas,

On Tuesday 14 September 2010 6:41:13 pm Juan Lucas Dominguez Rubio wrote:
> - If I remember it well, the gdal you get by using apt-get or similar does
> not include the ECW compressor, but I think the binaries from the FWTools
> website do, though I cannot test it right now:
> 
> http://home.gdal.org/fwtools/FWTools-linux-2.0.6.tar.gz
> 
> Your experience suggests otherwise? 

Ubuntu GDAL libraries keep resetting to version without ECW. Even the Ubuntu 
FWTools has reset. I keep setting up the system only to have it reset by 
itself.

> Which error message do you get when trying to create a ECW?

None really. It is just that the library does not recognise ECW format.

> gdal_translate -of ecw image.jpg image.ecw

Yeap. I found similar examples on the GDAL site and several HowTo websites.

The only way to get the FWTools to work was install it on a Windows machine 
then using the export tool.

> - Have you tried compressed TIF?

No. Is it fast?

Do you know of anyone who has compiled a matrix of image formats against 
compression, retention of image integrity (~loss of detail) and rewrite time 
while panning (particularly in gvSIG)?

ECW files are touted as the best compression-image quality retention-rewrite 
combination: certainly in Australia it is the primary format used in natural 
resource management by consultants and government agencies. Is this hype, or 
does the format really hold the title?

> ________________________________
> 
> De: gvsig_internacional-bounces at listserv.gva.es en nombre de Simon Cropper
> (Botanicus Australia Pty Ltd) Enviado el: mar 14/09/2010 9:07
> Para: Users and Developers mailing list
> Asunto: [Gvsig_english] QUESTION gvSIG -- Image files with fast rewrites
> 
> 
> 
> Hi,
> 
> Most of my clients provide aerial photography in ECW format. These images
> provide high resolution, are relatively small and quickly rewrite on the
> screen when panning.
> 
> Lately I have been getting JPG files. These files however are quite big and
> take significantly longer time to rewrite.
> 
> What is an alternative image format to ECW in the 'open free' environment?
> Something GDAL can be used to convert from JPG without jumping through
> hoops.
> 
> Ideally the file sizes should be low despite the high resolution, gvSIG
> able to read it natively and is quick to rewrite when panning.
> 
> Any suggestions would be appreciated.
> 
> PS. I know gdal_translate can, supposedly convert between JPG and ECW, but
> despite many attempts I have been unable to get this to work. I am looking
> for something else, if possible, that has the same intrinsic properties
> but is recognized by default in the gdal libraries so that every time I
> get an update of the 'free' Ubuntu version the FWTools or alternative
> 'commercially enabled' version is not replaced.

-- 
Cheers Simon

	Simon Cropper
	Botanicus Australia Pty Ltd
	PO Box 160 Sunshine 3020
	P: 03 9311 5822. M: 041 830 3437
	W: http://www.botanicusaustralia.com.au